How it works
The formula
buy the cheapest mix of kits whose coverage adds up to at least that
Assumptions
- Kit coverage is for water-based two-part kits like Rust-Oleum EpoxyShield: the 1-car kit covers up to 250 sq ft a coat on smooth concrete and the 2.5-car kit up to 500. On rough, porous concrete Rust-Oleum gives 125 to 200 sq ft for the 1-car kit; we use 160 (64% of smooth) for both sizes.
- Prices: about $95–$115 for a 1-car kit and $150–$185 for a 2.5-car kit (checked Oct 2026). We pick the mix that's cheapest at the middle of those prices, or at your prices if you type them.
- Not included: a degreaser and concrete etch for prep, decorative flakes and a clear topcoat, which some kits include and some sell separately.
- Professional 100% solids epoxy goes on much thicker: about 160 sq ft per gallon at 10 mils (Duraamen's coverage chart), so it takes more product per square foot but lasts longer.
Worked example
A 22 × 22 ft two-car garage, one coat, smooth concrete
- 22 × 22 = 484 sq ft of coverage for one coat
- One 2.5-car kit covers 500 sq ft: 1 kit, cheaper than two 1-car kits
- On rough concrete each 2.5-car kit covers about 320 sq ft, so it takes 2 × 2.5-car
Kits for common garage sizes
| Garage | Sq ft | 1 coat | 2 coats |
|---|---|---|---|
| 1-car (12 × 22 ft) | 264 | 1 × 2.5-car | 1 × 2.5-car + 1 × 1-car |
| 2-car (22 × 22 ft) | 484 | 1 × 2.5-car | 2 × 2.5-car |
| 2-car, deep (24 × 24 ft) | 576 | 1 × 2.5-car + 1 × 1-car | 2 × 2.5-car + 1 × 1-car |
| 3-car (32 × 22 ft) | 704 | 1 × 2.5-car + 1 × 1-car | 3 × 2.5-car |
Questions people ask
How much epoxy do I need for a 2-car garage?
A typical 22 × 22 ft two-car garage is 484 sq ft: one 2.5-car kit covers it in one coat on smooth concrete. Rough or porous concrete soaks up more, so plan on 2 × 2.5-car. Two coats doubles it.
Do I need one coat or two?
Water-based DIY kits are often one coat over sound, clean concrete; a second coat gives a thicker, tougher finish and hides stains and patches better. Follow the kit's instructions, and buy for two coats if the floor is rough, stained or heavily used.
What prep does epoxy need?
Clean, dry, etched concrete. Degrease oil spots, etch or grind so the coating can bite, and test for moisture: tape a plastic sheet down for 24 hours (Rust-Oleum's EpoxyShield instructions), and if it's damp underneath, the floor isn't ready. Most failures are prep failures.
How long does an epoxy garage floor last?
A DIY water-based kit typically lasts a few years under car traffic before it wears or peels where tires sit; thick 100% solids systems put down by pros can last many years. Hot tires on a fresh coat cause "hot tire pickup", so wait the full cure time before parking.
Can I epoxy in winter?
Only if the concrete and air stay warm enough: most kits want the floor and air above about 50 to 60°F through the cure, and the concrete must be dry. Check your kit's label; a cold, damp garage is the most common reason a coating fails.